Copperheads are common across the southeastern US, and are responsible for a significant number of crotalid envenomations in areas where they are endemic. However, they have the least potent venom of all the pit vipers, and often bites are self-limiting. Prior to development of CroFab, copperhead bites were generally not given antivenom, as the risks of the Wyeth product were felt too high for minimal benefits. Now, CroFab is felt to be safe enough to mitigate even mild symptoms of copperhead envenomations.
However, physicians typically work up copperhead bites the same way they do the other crotalid species. This includes chemistry, complete blood count, and coagulation studies. And often patients are admitted for serial checks of these lab values even if there are no significant physical exam findings. But are these really necessary when the snake is clearly identified as a copperhead?
These authors suggest that it isn’t. They examined more than 10 years of data from their 2 hospitals in St. Louis and found 106 “probable” or confirmed copperhead bites. Of these, 6 had abnormal coagulation studies, all were minimally outside of normal limits. None had bleeding complications either. Thus, the utility of coagulation studies in copperhead bites is suspect.
So can we stop checking coags on these patients? It’s a decent consideration, in the absence of evidence of coagulopathy. More importantly, patients don’t need to be admitted for serial coagulation studies if the snake in question is definitively a copperhead. Perhaps checking an initial lab, and if it it’s normal, send them home if no other concerning symptoms. However, if you’re considering giving antivenom, you’re not saving any money by not checking, and you’re probably not sending that patient home.
Ali AJ, Horwitz DA, Mullins ME. Lack of coagulopathy after copperhead snakebites. Ann Emerg Med. 2015 Apr;65(4):404-9 [PMID 25199611]
EBM Gone Wild